The present invention relates to a steel frame structure, and more particularly, to a steel frame structure using U-shaped composite beams that is capable of improving the constructability and structural performance in the connected portions between columns and girders and between the girders and beams.
A steel frame structure (or a steel structure) and a steel frame structured reinforced concrete structure are representative examples of modern construction methods, and they are applied to a wide range of constructions from warehouses having a relatively simple structure to high-rise buildings, hangar decks, gymnasiums, airports, and factories requiring large-sized space. The steel frame structure has a variety of structural shapes in accordance with its size and purpose and accordingly adopts different materials and connecting methods in response to its structural shapes. Examples of the steel frame structure are a frame structure, a truss structure, a gable frame, a steel pipe structure, and a light weight steel frame structure.
The frame structure of the steel frame structure is made by forming a lattice type frame structure with all kinds of columns and beams. In this case, slabs or horizontal braces are used as side-force reinforcing parts, and shear walls are appropriately arranged. The frame structure is popularized in recent high-rise buildings as well as medium or less-rise buildings because of its structural simplicity and the easiness in the construction thereof.
Structural members constituting the frame structure are columns, beams, and slabs, and the beams include steel beams, built-up beams, lattice beams, honeycomb beams, and composite beams with concrete.
One of the prior art is disclosed in Korean Patent No. 0617878 entitled “molded steel plate concrete beam”. The conventional molded steel plate concrete beam includes a U-shaped permanent mold made by integrating two L-shaped steel plates with each other by means of welding, and the U-shaped permanent mold has top flanges, bottom flanges and web plates. Shear connectors are attached to the top flanges in such a manner as to be integrated with slab concrete, and the bottom flanges have a Y-shaped protrusion formed on the center portion thereof to increase the section and the composition effects of the concrete cast in the interior thereof, so that the concrete is cast into the U-shaped permanent mold to allow the U-shaped permanent mold to be integrated with an external permanent mold plate.
According to the above-mentioned prior art, however, the two L-shaped steel plates are integrated as a unitary body by means of the welding, so that the whole shape becomes complicated, and bending, cutting and welding for making the structure are needed, thereby making it hard to manufacturing the structure. Since the molded steel plate concrete beam is different from existing steel beams, further, the connecting way between columns and beams are different from that in the existing steel structure, so that the molded steel plate concrete beam does not make use of the existing steel structure connecting way like existing bracket type beam connection.
Another example of the prior art is disclosed in Korean Utility Model Registration No. 0420294 entitled “asymmetric H-shaped beam”. The asymmetric H-shaped beam includes top and bottom flanges having different widths from each other and a web formed vertically between the top and bottom flanges, the web having at least one or more through-holes formed thereon, through which wire members are passed.
In the above-mentioned another example of the prior art, however, the top flange is formed over the whole length of the web even in the region where positive moment action is generated, so that the quantity of steel materials consumed is increased to cause high production costs, and the whole self-weight of the beam is also increased. Further, the web has the through holes for improving the composition effects, so that the shape of the section of the web becomes complicated and the cutting processes are increased during manufacturing to cause high production costs and construction costs.
Yet another example of the prior art is disclosed in Korean Patent No. 0851490 entitled “steel composite beam structure for saving story height”. The steel composite beam structure includes I-shaped steel beams having webs, top flanges, and bottom flanges, the bottom flanges having the widths larger than the top flanges and the webs having web holes formed on the center thereof in such a manner as to be spaced apart from each other by a given distance in the state of being far from the top flanges and the bottom flanges. Further, the bottom flanges have -shaped support plates extended from both ends thereof along the direction of the length of the steel beams, and a deck plate mounted on the -shaped support plates, onto which slab concrete is cast. The web holes have a trapezoidal shape having the upper base side being shorter in length than the lower base, and the -shaped support plates are coupled to both ends of the bottom flanges by means of seam welding or are integrated with the bottom flanges. The steel beams are divided into the girder having a long depth and the beam having a short depth, and when the girder and the beam are connected to each other at a given angle, the -shaped support plate of the beam is mounted on the -shaped support plate of the girder. Also, the web holes of the girder are positioned between the top surface of the -shaped support plate of the beam and the top surface of -shaped support plate of the girder in such a manner as to allow a duct to be passed therethrough.
In the above-mentioned yet another example of the prior art, however, the top flanges are formed over the whole lengths of the webs, so that the quantity of steel materials consumed is increased to cause high production costs, and further, the web holes are formed on the webs to obtain the composition effects, so that the shapes of the sections of the webs become complicated and the cutting processes are increased during manufacturing to cause high production costs and construction costs. Additionally, the beam is mounted on the top of the girder, so that it is hard to perform the construction, and since the sectional shapes and depths between the girder and the beam are different from each other, the connecting way between column and beam is different from that in existing steel structure, so that the steel composite beam structure does not make use of the existing steel structure connecting way like existing bracket type beam connection.